﻿using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Data;
using System.Data.Common;
using System.Diagnostics;
using System.Reflection;
using System.Text;

namespace BigfootSQL 
{
    /// <summary>
    /// This is a simple SQL syntax builder helper class. It aids in the creation of a SQL statement
    /// by auto creting parameters, as well as preventing against injection attacks etc. It also uses 
    /// the DAAB class and ObjectHelper classes to execute the query and hydrate the Model objects.
    /// 
    /// It was designed with simplicity and speed in mind. It is a great replacement to writing
    /// directly against the ADO.NET providers. It is not meant to be a full ORM but rather a rapid query
    /// execution and object hydration helper.
    /// 
    /// It uses a fluid interface for simplicity of code. You must know how to write SQL as it is a light
    /// SQL code builder while automating the rest. It does not generate SQL for you, rather it makes the 
    /// writing, executing, and results mapping simple.
    /// 
    /// Examples (Assumes there is a DB variable of type SqlHelper):
    ///     Select a list of orders:
    ///         List<OrderListItem> obj;
    ///         obj = DB.SELECT("OrderID, OrderDate, ShipToCity").FROM("Orders").WHERE("ShipToState","FL").ExecuteCollection<OrderListItem>();
    ///     
    ///     Select a single value typed to the correct type:
    ///         datetime d;
    ///         d = DB.SELECT("OrderDate").FROM("Orders").WHERE("OrderID",OrderID).ExecuteScalar<datetime>()
    /// 
    /// It has several other Execute methods to retreive DataReaders, DataSets, and many others. Also has ExecuteNonQuery for executing 
    /// void queries.
    /// </summary>
    public class SqlHelper
    {

        #region "Constructors / Private variables"

        StringBuilder _sql = new StringBuilder();
        List<DbParameter> _params = new List<DbParameter>();
        public string ConnectionString;


        // See more constructors bellow for dotnetnuke integration
        public SqlHelper(){}
        public SqlHelper(string connectionString)
        {
            ConnectionString = connectionString;
        }

        #endregion


        #region "SQL Builder methods"

        public StringBuilder RawBuilder
        {
            get { return _sql; }
        }
        
        /// <summary>
        /// Add literal SQL statement to the query
        /// </summary>
        /// <param name="sql">SQL Fragment to add</param>
        public SqlHelper Add(string sql)
        {
            return Append(sql);
        }

        private SqlHelper Append(string sql)
        {
            if (_sql.Length > 0) sql = " " + sql + " ";
            //if (_sql.Length > 0 && sql.EndsWith(" ") == false) _sql.Append(" ");
            _sql.Append(Translate(sql));
            return this;
        }

        /// <summary>
        /// Add a parameter to a WHERE statement. Will generate ColumnName = 'Value' (quotes only added if it is a string)
        /// </summary>
        /// <param name="wherecolumn">The name of the column to search</param>
        /// <param name="value">The value to search for</param>
        public SqlHelper Add(string wherecolumn, object value)
        {
            return Add(wherecolumn, "=", value, false);
        }

        /// <summary>
        /// Add a paramter to a WHERE statement. Will generate ColumnName {Operator} 'Value' (quotes only added if it is a string)
        /// </summary>
        /// <param name="wherecolumn">The of the column to search</param>
        /// <param name="value">The value to search for. If it is a string it is properly espaped etc.</param>
        /// /// <param name="isSet">Identifies this comparison as a set statement. Needed for setting null values</param>
        public SqlHelper Add(string wherecolumn, object value, bool isSet )
        {
            return Add(wherecolumn, "=", value, isSet);
        }

        /// <summary>
        /// Add a paramter to a WHERE statement. Will generate ColumnName {Operator} 'Value' (quotes only added if it is a string)
        /// </summary>
        /// <param name="wherecolumn">The of the column to search</param>
        /// <param name="operator">The operator for the search. e.g. = <= LIKE <> etc.</param>
        /// <param name="value">The value to search for. If it is a string it is properly espaped etc.</param>
        public SqlHelper Add(string wherecolumn, string @operator, object value)
        {
            return Add(wherecolumn, @operator, value, false);
        }

        /// <summary>
        /// Add a paramter to a WHERE statement. Will generate ColumnName {Operator} 'Value' (quotes only added if it is a string)
        /// </summary>
        /// <param name="wherecolumn">The of the column to search</param>
        /// <param name="operator">The operator for the search. e.g. = <= LIKE <> etc.</param>
        /// <param name="value">The value to search for. If it is a string it is properly espaped etc.</param>
        /// <param name="isSet">Identifies this comparison as a set statement. Needed for setting null values</param>
        public SqlHelper Add(string wherecolumn, string @operator, object value, bool isSet)
        {
            if (value == null)
            {
                Add(wherecolumn);
                return isSet ? Add("= NULL") : 
                               Add("IS NULL");
            }
            else
                return Add(wherecolumn).Add(@operator).Add(AddTempParam(value));
        }

        public SqlHelper LIKE(string wherecolumn, string value)
        {
            return Add(wherecolumn).Add("LIKE").Add("'%" + EscapeForLike(value,true) + "%'");
        }

        public SqlHelper StartsWith(string wherecolumn, string value)
        {
            return Add(wherecolumn).Add("LIKE").Add("'" + EscapeForLike(value, true) + "%'");
        }

        public SqlHelper EndsWith(string wherecolumn, string value)
        {
            return Add(wherecolumn).Add("LIKE").Add("'%" + EscapeForLike(value, true) + "'");
        }

        public SqlHelper Contains(string wherecolumn, string value)
        {
            return LIKE(wherecolumn, value);
        }

        public SqlHelper LIKE(string wherecolumn, string value, bool fullTextSearch)
        {
            if (!string.IsNullOrEmpty(value) && fullTextSearch)
            {
                var firstWord = true;
                OpenParenthesis();
                foreach (var term in value.Split(' '))
                {
                    if (firstWord) firstWord = false; else AND();
                    LIKE(wherecolumn, term);
                }
                CloseParenthesis();
                return this;
            }
            else
            {
                return LIKE(wherecolumn, value);
            }
        }

        public SqlHelper SELECT(string sql)
        {
            return Add("SELECT " + sql);
        }

        public SqlHelper CASE()
        {
            return Add("CASE");
        }

        public SqlHelper CASE(string condition, string trueResult, string falseResult)
        {
            return CASE().WHEN(condition, trueResult).ELSE(falseResult).END();
        }

        public SqlHelper AS(string columnName)
        {
            return Add("AS " + columnName);
        }

        public SqlHelper WHEN(string condition, string trueResult)
        {
            return Add(string.Format("WHEN {0} THEN {1}", condition, trueResult));
        }

        public SqlHelper ELSE(string elseResult)
        {
            return Add("ELSE " + elseResult);
        }

        public SqlHelper END()
        {
            return Add("END");
        }

        /// <summary>
        /// Used to returned a paged result set
        /// </summary>
        /// <param name="columns">Columns to include in the paged result. When paging this you can specify columns only once</param>
        /// <param name="pageorderby">This is used to generate the RowNumber field resulting in: 
        /// ROW_NUMBER() OVER(ORDER BY Field1, Field2) AS RowNumber </param>
        /// <param name="pageSize">How many records per page</param>
        /// <returns></returns>
        public SqlHelper SELECTPAGED(string columns, string pageorderby, int pageSize)
        {
            //_pageorderby = pageorderby;
            _pageSize = pageSize;
            return Add("SELECT " + columns + ", ROW_NUMBER() OVER(ORDER BY " + pageorderby + " ) AS RowNumber");
        }
        //private string _pageorderby;
        private int _pageSize;

        /// <summary>
        /// Call this function to identify which page to get. Must be called at the end of the statement.
        /// </summary>
        /// <param name="currentpage">The current page (0 based)</param>
        public SqlHelper PAGE(int currentpage)
        {
            var rowStart = _pageSize * currentpage;
            var rowEnd = (_pageSize * currentpage) + _pageSize + 1;
            _sql.Insert(0, "SELECT * FROM (");
            _sql.AppendFormat(") PagedResult WHERE RowNumber > " + rowStart + " AND RowNumber < " + rowEnd);
            //_sql.AppendFormat(") PagedResult WHERE RowNumber > @StartRow AND RowNumber < @EndRow ORDER BY " + _pageorderby);
            return this;
        }
        
        public SqlHelper SELECT_ALL_FROM(string tablename)
        {
            return Add("SELECT * FROM").Add(Translate(tablename));
        }

        public SqlHelper SELECT_ALL_FROM(string tablename, int topCount)
        {
            return Add("SELECT TOP  " + topCount + " * FROM").Add(Translate(tablename));
        }

        public SqlHelper SELECT_COUNT_ALL_FROM(string tablename)
        {
            return Add("SELECT COUNT(*) FROM").Add(Translate(tablename));
        }
        
        public SqlHelper SELECT(params string[] columns)
        {
            var s = "SELECT ";
            var firstcolumn = true;
            foreach (string c in columns)
            {
                if (firstcolumn) {
                    s += columns;
                    firstcolumn = false;
                }
                else
                {
                    s += ", " + c;
                }
            }
            return Add(s);
        }

        public SqlHelper SELECT_IDENTITY()
        {
            return Add("SELECT @@IDENTITY");
        }

        public SqlHelper INNERJOIN(string sql)
        {
            return Add("INNER JOIN " + sql);
        }

        public SqlHelper LEFTJOIN(string sql)
        {
            return Add("LEFT JOIN " + sql);
        }

        public SqlHelper ON(string sql)
        {
            return Add("ON " + sql);
        }

        public SqlHelper ON(string leftcolumn, string rightcolumn)
        {
            return Add("ON " + leftcolumn + " = " + rightcolumn);
        }

        public SqlHelper FROM(string sql)
        {
            return Add("FROM " + sql);
        }

        public SqlHelper WHERE()
        {
            return Add("WHERE");
        }

        public SqlHelper WHERE(string sql)
        {
            return Add("WHERE " + sql);
        }

        public SqlHelper WHERE(string columnname, object value)
        {
            return Add("WHERE").Add(columnname, value);
        }

        public SqlHelper WHERE(string columnname, string @operator, object value)
        {
            return Add("WHERE").Add(columnname, @operator, value);
        }

        public SqlHelper IN(string columnname, int value)
        {
            return Add(columnname + " IN (" + value + ")");
        }

        public SqlHelper IN(string columnname, string value)
        {
            return Add(columnname + " IN ('" + EscapeApostrophe(value) + "')");
        }

        public SqlHelper IN(string columnname, params string[] values)
        {

            return Add(columnname + " IN (" + ArrayToINstring(values) + ")");
        }

        public SqlHelper IN(string columnname, params int[] values)
        {

            return Add(columnname + " IN (" + ArrayToINint(values) + ")");
        }

        public SqlHelper ORDERBY(string sql)
        {
            return Add("ORDER BY " + sql);
        }

        public SqlHelper GROUPBY(string sql)
        {
            return Add("GROUP BY " + sql);
        }

        public SqlHelper HAVING(string sql)
        {
            return Add("HAVING " + sql);
        }

        public SqlHelper INSERTINTO(string tablename, string columns)
        {
            return Add("INSERT INTO " + tablename + "(" + columns + ")");
        }

        public SqlHelper OP()
        {
            return OpenParenthesis();
        }

        public SqlHelper OpenParenthesis()
        {
            return Add("(");
        }

        public SqlHelper OP(string wherecolumn, object value)
        {
            return OpenParenthesis(wherecolumn, value);
        }

        public SqlHelper OpenParenthesis(string wherecolumn, object value)
        {
            return Add("(").Add(wherecolumn,value);
        }

        public SqlHelper CP()
        {
            return CloseParenthesis();
        }

        public SqlHelper CloseParenthesis()
        {
            return Add(")");
        }

        public SqlHelper UPDATE(string sql)
        {
            return Add("UPDATE " + sql);
        }

        public SqlHelper SET()
        {
            return Add("SET");
        }

        public SqlHelper SET(string columnname, object value)
        {
            AddIfNotFound("SET");
            
            if (!_sql.ToString().TrimEnd().EndsWith(" SET") && 
                !_sql.ToString().TrimEnd().EndsWith(","))
                Add(",");

            Add(columnname, value, true);

            return this;
        }

        public SqlHelper DELETEFROM(string sql)
        {
            return Add("DELETE FROM " + sql);
        }

        public SqlHelper AND()
        {
            return Add("AND");
        }

        public SqlHelper AND(string sql)
        {
            return Add("AND " + sql);
        }

        public SqlHelper AND(string column, object value)
        {
            return Add("AND").Add(column, value);
        }

        public SqlHelper AND(string column, string @operator, object value)
        {
            return Add("AND").Add(column, @operator, value);
        }

        public SqlHelper AND_BETWEEN(string column, DateTime startValue, DateTime endValue)
        {
            return AND().BETWEEN(column, startValue, endValue);
        }

        public SqlHelper BETWEEN(string column, object startValue, object endValue)
        {
            return Add(column + " BETWEEN " + AddTempParam(startValue) + " AND " + AddTempParam(endValue));
        }
        
        public SqlHelper OR() 
        {
            return Add("OR"); 
        }

        public SqlHelper OR(string sql)
        {
            return Add("OR " + sql);
        }

        public SqlHelper OR(string column, object value)
        {
            return Add("OR").Add(column, value);
        }

        public SqlHelper OR(string column, string @operator, object value )
        {
            return Add("OR").Add(column, @operator, value);
        }

        public SqlHelper OR_BETWEEN(string column, DateTime startValue, DateTime endValue)
        {
            return OR().BETWEEN(column, startValue, endValue);
        }

        public SqlHelper VALUES(string sql)
        {
            return Add("VALUES ( " + sql + " ) ");
        }

        public SqlHelper VALUES(params object[] ps)
        {
            Add("VALUES (");
            var first = true;
            foreach (var p in ps)
            {
                if (first) 
                {
                    Add(AddTempParam(p));
                    first = false;
                }
                else
                {
                    Add(",").Add(AddTempParam(p));
                }
            }
            return Add(")");
        }

        public SqlHelper DECLARE(string varname, string vartype)
        {
            if (varname.StartsWith("@")==false ) varname = "@" + varname;
            return Add("DECLARE " + varname + ((vartype.ToLower() == "table") ? " AS " : " ") + vartype);
        }

        public SqlHelper DECLARE(string varname, string vartype, object value)
        {
            if (varname.StartsWith("@")==false ) varname = "@" + varname;
            return DECLARE(varname, vartype).Add("SET " + varname + " = " + AddTempParam(value));
        }

        public SqlHelper DECLARE_TABLE(string varname, string columns)
        {
            return DECLARE(varname, "TABLE").Add("( " + columns + " )");
        }

        /// <summary>
        /// Execute a StoredProcedure. By passing the SP name and a list values as parameters to the SP
        /// </summary>
        /// <param name="spname">SP Name</param>
        /// <param name="ps">Parameters for the Stored Procedure in the proper order</param>
        public SqlHelper EXECUTE(string spname, params object[] ps)
        {
            Add("EXECUTE " + spname);
            var first = true;
            foreach (var p in ps)
            {
                if (first)
                    first = false;
                else
                    Add(",");

                Add(AddTempParam(p));
            }
            return this;
        }

        /// <summary>
        /// Execute a function by passing the function anem of and a list of paremters. 
        /// e.g. SELECT_SCALARFUNCTION("GetOrderName", OrderDate, CustomerID)
        /// </summary>
        /// <param name="fname">Name of the function</param>
        /// <param name="ps">List of parameters values to pass into the function. Must be in the right order</param>
        public SqlHelper SELECT_SCALARFUNCTION(string fname, params object[] ps)
        {
            Add("SELECT " + fname + "(");
            var first = true;
            foreach (var p in ps)
            {
                if (first)
                    first = false;
                else
                    Add(",");

                Add(AddTempParam(p));
            }
            Add(")");
            return this;
        }

        private void AddIfNotFound(string statement)
        {
            if (_sql.ToString().IndexOf(statement) == -1)
            {
                Add(statement);
            }
        }

        #endregion

        
        #region "AddParam / AddTempParam"
        
        /// <summary>
        /// Adds a parameter with the provided value and returns the created parameter name
        /// Used when creating dynamic queries and the parameter is not important outside of the inmediate query
        /// Used internally to auto created parameters for the WHERE AND OR and other statements
        /// </summary>
        /// <param name="value">The value of the parameter</param>
        /// <returns>The generated name for the parameter</returns>
        public string AddTempParam(object value)
        {
            var name = "_tempParam" + _params.Count;
            AddParam(name, value);
            return "@" + name;
        }

        /// <summary>
        /// Adds a named parameter to the query
        /// </summary>
        /// <param name="name">The name of the parameter</param>
        /// <param name="value">The value of the paremter</param>
        public SqlHelper AddParam(string name, object value)
        {
            if (name.StartsWith("@")) name=name.Substring(1);
            var param = DAAB.ProviderFactory().CreateParameter();
            param.ParameterName = name;
            param.Value = value;
            _params.Add(param);
            return this;
        }

        private bool HasParams
        {
            get { return _params.Count > 0; }
        }

        #endregion


        #region "ToString / DebugSql / Clear"

        /// <summary>
        /// Clear the current query
        /// </summary>
        public void Clear()
        {
            _sql = new StringBuilder();
            _params=new List<DbParameter>();
        }

        /// <summary>
        /// Auto writes the finished statement as close as possible.
        /// </summary>
        public override string ToString()
        {
            Debug.WriteLine(DebugSql);
            return _sql.ToString();
        }
        
        /// <summary>
        /// Creates an executable SQL statement including declaration of SQL parameters for debugging purposes.
        /// </summary>
        public string DebugSql
        {
            get
            {
                var value = "====NEW QUERY====\r\n";
                foreach (DbParameter param in _params)
                {
                    var addQuotes = (param.DbType == DbType.String);
                    value += "DECLARE @" + param.ParameterName + " " + param.DbType;
                    if (param.Value == null)
                        value += " SET @" + param.ParameterName + " = NULL";
                    else
                        value += " SET @" + param.ParameterName + " = " + 
                                    ((addQuotes) ? "'" + EscapeApostrophe(param.Value.ToString()) + "'"
                                                 : EscapeApostrophe(param.Value.ToString()));
                    value += "\r\n";
                }
                value += _sql + "\r\n";
                
                //Add \r\n before each of these words
                string[] words = { "SELECT", "FROM", "WHERE", "INNER JOIN", "LEFT JOIN", "ORDER BY", "GROUP BY", "DECLARE", 
                                     "SET", "VALUES", "INSERT INTO", "DELETE FROM", "UPDATE" };
                foreach (string w in words)
                    value = value.Replace(w, "\r\n" + w);
                
                // Return the value
                return value;
            }
        }

        #endregion


        #region "DotNetNuke integration: Translate | GetName"

        public String Owner;
        public String Qualifier;
        public String ModuleQualifier;

        public SqlHelper(string owner, string qualifier)
        {
            if (!String.IsNullOrEmpty(owner) && !owner.EndsWith("."))
                owner += ".";

            if (!String.IsNullOrEmpty(qualifier) && !qualifier.EndsWith("_"))
                qualifier += "_";

            Owner = owner;
            Qualifier = qualifier;
        }
        public SqlHelper(string owner, string qualifier, string moduleQualifier)
        {
            if (!String.IsNullOrEmpty(owner) && !owner.EndsWith("."))
                owner += ".";

            if (!String.IsNullOrEmpty(qualifier) && !qualifier.EndsWith("_"))
                qualifier += "_";

            if (!String.IsNullOrEmpty(moduleQualifier) && !moduleQualifier.EndsWith("_"))
                moduleQualifier += "_";

            Owner = owner;
            Qualifier = qualifier;
            ModuleQualifier = moduleQualifier;            
        }
        public SqlHelper(string owner, string qualifier, string moduleQualifier, string connectionString)
        {
            if (!String.IsNullOrEmpty(owner) && !owner.EndsWith("."))
                owner += ".";

            if (!String.IsNullOrEmpty(qualifier) && !qualifier.EndsWith("_"))
                qualifier += "_";

            if (!String.IsNullOrEmpty(moduleQualifier) && !moduleQualifier.EndsWith("_"))
                moduleQualifier += "_";

            Owner = owner;
            Qualifier = qualifier;
            ModuleQualifier = moduleQualifier;
            ConnectionString = connectionString;
        }

        /// <summary>
        /// Used to support DotNetNuke queries where database object names
        /// are dynamic based on the prefix of the installation.
        /// By using {{{TableName}}} it will translate into a proper DNN core table name
        /// By using {{TableName}} it will translate into a proper custom DNN Module table name
        /// </summary>
        /// <param name="sql">The sql fragment to translate</param>
        /// <returns>The translated string</returns>
        public string Translate(string sql)
        {
            // Translate databaseOwner and objectQualifier tokens
            sql = sql.Replace("{databaseOwner}", Owner);
            sql = sql.Replace("{objectQualifier}", Qualifier);

            // Get the tokens for Core {{{tablename}}} and Module {{tablename}}
            var tokens = GetTokens(sql,"{{{", "}}}");
            GetTokens(sql,tokens,"{{", "}}");
            
            // Replace the tokens
            if (tokens.Count > 0)
                foreach (var t in tokens.Keys)
                {
                    sql = sql.Replace(t, 
                                      t.StartsWith("{{{") ? GetName(tokens[t], false) 
                                                          : GetName(tokens[t], true)
                                      );
                }


            // Return the translated sql
            return sql;
        }

        //private string GetName(string name)
        //{
        //    return name.StartsWith("{{{") ? GetName(name, false) : 
        //                                    GetName(name, true);
           
        //}

        private string GetName(string name, bool addModuleQualifier)
        {
            var value = Owner + Qualifier;
            if (!string.IsNullOrEmpty(ModuleQualifier) &&  addModuleQualifier)
                value += ModuleQualifier;
            value += name;
            return value;
        }


        #endregion
        

        #region "Static Methods"
        /// <summary>
        /// Converts a collection of int into a value list to be used in and IN statement
        /// </summary>
        /// <param name="ps">List of int values</param>
        /// <returns>Properly formatted list for IN statement</returns>
        public static string ArrayToINint(params int[] ps)
        {
            var result = "";
            foreach (var p in ps)
            {
                if (result.Length > 0) result += ", ";
                result += p.ToString();
            }
            return result;
        }

        /// <summary>
        /// Converts a collection of int into a value list to be used in and IN statement
        /// </summary>
        /// <param name="ps">List of int values</param>
        /// <returns>Properly formatted list for IN statement</returns>
        public static string ArrayToINstring(params string[] ps)
        {
            var result = "";
            foreach (var p in ps)
            {
                if (result.Length > 0) result += ", ";
                result += "'" + EscapeApostrophe(p) + "'";
            }
            return result;
        }

        /// <summary>
        /// Escapes the apostrophe on strings
        /// </summary>
        /// <param name="sql">SQL statement fragment</param>
        /// <returns>The clean SQL fragment</returns>
        public static string EscapeApostrophe(string sql)
        {
            sql = sql.Replace("'", "''");
            return sql;
        }

        /// <summary>
        /// Properly excapes a string to be included in a LIKE statement
        /// </summary>
        /// <param name="value">Value to search for</param>
        /// <param name="escapeApostrophe">Weather to escape the apostrophe. Prevents double escaping of apostrophes</param>
        /// <returns>The transalted value ready to be used in a LIKE statement</returns>
        public static string EscapeForLike(string value, bool escapeApostrophe)
        {
            // Do not process a string that is null or empty
            if (string.IsNullOrEmpty(value)) return value;

            string[] specialChars = {"%", "_", "-", "^"};
            string newChars;

            // Escape the [ braket
            newChars = value.Replace("[", "[[]");

            // Replace the special chars
            foreach (string t in specialChars){
                newChars = newChars.Replace(t, "[" + t + "]");
            }

            // Escape the apostrophe if requested
            if (escapeApostrophe)
                newChars = EscapeApostrophe(newChars);

            return newChars;
        }

        /// <summary>
        /// Retreives a list of tokens included in a string
        /// </summary>
        /// <param name="s">The string object being exteded</param>
        /// <param name="startDelimiter">The start delimiter for the token</param>
        /// <param name="endDelimiter">The end delimiter for the token</param>
        /// <returns>A dictionary of tokens present in the string</returns>
        public static Dictionary<string, string> GetTokens(string s, string startDelimiter, string endDelimiter)
        {
            return GetTokens(s, new Dictionary<string, string>(), startDelimiter, endDelimiter);
        }

        /// <summary>
        /// Retreives a list of tokens included in a string
        /// </summary>
        /// <param name="s">The string object being exteded</param>
        /// <param name="startDelimiter">The start delimiter for the token</param>
        /// <param name="endDelimiter">The end delimiter for the token</param>
        /// <param name="tokens">The dictionary of tokens to add the new finds to</param>
        /// <returns>A dictionary of tokens present in the string</returns>
        public static Dictionary<string, string> GetTokens(string s, Dictionary<string, string> tokens, string startDelimiter, string endDelimiter)
        {
            var marker = 0;
            do
            {
                // Get the start and end of the tokens
                var startIndex = s.IndexOf(startDelimiter, marker);
                int endIndex;

                if (startIndex > -1)
                    endIndex = s.IndexOf(endDelimiter, startIndex);
                else
                    break;

                // Add the token and increase the marker
                if (endIndex > -1)
                {
                    var token = s.Substring(startIndex, (endIndex + endDelimiter.Length) - startIndex);
                    var tokenValue = token.Substring(startDelimiter.Length, token.Length - (startDelimiter.Length + endDelimiter.Length));
                    tokens.Add(token, tokenValue);
                    marker = endIndex + endDelimiter.Length;
                }

            } while (marker < s.Length);

            return tokens;
        }
        #endregion


        #region "Execute SQL"

        /// <summary>
        /// Executes the query and returns a Scalar value
        /// </summary>
        /// <returns>Object (null when dbnull value is returned)</returns>
        public object ExecuteScalar()
        {
            var rvalue = (HasParams)
                                ? DAAB.ExecuteScalar(ConnectionString, CommandType.Text, ToString(), _params.ToArray())
                                : DAAB.ExecuteScalar(ConnectionString, CommandType.Text, ToString());
            
            if (rvalue == DBNull.Value) rvalue = null;

            return rvalue;
        }

        /// <summary>
        /// Executes the query and returns a Scalar value for the specific generic value
        /// </summary>
        /// <returns>A typed object of T</returns>
        public T ExecuteScalar<T>()
        {
            var rvalue = ExecuteScalar();
            if (rvalue != null)
            {
                var tc = TypeDescriptor.GetConverter(typeof(T));
                return (T)tc.ConvertFromInvariantString(rvalue.ToString());
            }
            
            return default(T);
        }

        /// <summary>
        /// Appends a SELECT @@IDENTITY statement to the query and then executes
        /// </summary>
        /// <returns>The identity of the just inserted record</returns>
        public int ExecuteScalarIdentity()
        {
            SELECT_IDENTITY();
            return ExecuteScalarInt();
        }

        /// <summary>
        /// Executes the query and returns a sclar value of type int
        /// </summary>
        public int ExecuteScalarInt()
        {
            return ExecuteScalar<int>();
        }

        /// <summary>
        /// Executes the query and returns a scalar value of type bool
        /// </summary>
        public bool ExecuteScalarBool()
        {
            return ExecuteScalar<bool>();
        }

        /// <summary>
        /// Executes the query and returns a sclar value of type string
        /// </summary>
        public string ExecuteScalarString()
        {
            return ExecuteScalar<string>();
        }

        /// <summary>
        /// Executes a query that does not return a value
        /// </summary>
        public int ExecuteNonquery()
        {
            return (HasParams)
                ? DAAB.ExecuteNonQuery(ConnectionString, CommandType.Text, ToString(), _params.ToArray())
                : DAAB.ExecuteNonQuery(ConnectionString, CommandType.Text, ToString());
        }

        /// <summary>
        /// Executes a query and hydrates an object with the result
        /// </summary>
        /// <typeparam name="T">The type of the object to hydrate and return</typeparam>
        /// <returns>I hydrated object of the type specified</returns>
        public T ExecuteObject<T>()
        {
            var reader = ExecuteReader();
            return FillObject<T>(reader);
        }

        /// <summary>
        /// Returns a dictionary of FieldName. Works like Scalar except it can 
        /// return multiple fields values for the first record of the resultset
        /// </summary>
        /// <returns>Dictionary with FieldName, Value</returns>
        public Dictionary<string, object> ExecuteValues()
        {
            var reader = ExecuteReader();
            try
            {
                Dictionary<string, object> values = null;
                if (reader.Read() == false) { return values; }
                values = new Dictionary<string, object>();
                for (int i = 0; i < 100; i++)
                {
                    try
                    {
                        var key = reader.GetName(i);
                        object value = null;
                        if (reader.IsDBNull(i) == false)
                        {
                            value = reader[i];
                        }
                        values.Add(key,value);
                    }
                    catch (IndexOutOfRangeException)
                    {
                        return values;
                    }
                }
                return values;
            } 
            finally 
            {
                reader.Close();
            }
        }

        /// <summary>
        /// Executes the query and returnes a collection of strings. 
        /// Useful when needing a quick lookup set of values
        /// </summary>
        /// <returns>A string collection</returns>
        public List<string> ExecuteStringCollection()
        {
            var reader = ExecuteReader();

            try
            {
                List<string> values = null;
                while (reader.Read())
                {   
                    if (reader.IsDBNull(0) == false)
                    {
                        if (values == null) values = new List<string>();
                        values.Add(reader[0].ToString());
                    }
                }
                return values;
            }
            finally
            {
                reader.Close();
            }
        }

        /// <summary>
        /// Executes the query and maps the results to a collection of objects 
        /// of the type specified through the generic argument
        /// </summary>
        /// <typeparam name="T">The of object for the collection</typeparam>
        /// <returns>A collection of T</returns>
        public List<T> ExecuteCollection<T>()
        {
            var reader = ExecuteReader();
            return FillCollection<T>(reader);
        }

        /// <summary>
        /// Executes the query and returns a DataReader
        /// </summary>
        public DbDataReader ExecuteReader()
        {
            return (HasParams)
                       ? DAAB.ExecuteReader(ConnectionString, CommandType.Text, ToString(), _params.ToArray())
                       : DAAB.ExecuteReader(ConnectionString, CommandType.Text, ToString());
        }

        /// <summary>
        /// Executes the query and returns a filled Dataset with the resultset
        /// </summary>
        /// <returns>A dataset</returns>
        public DataSet ExecuteDataset()
        {
           return (HasParams)
                   ? DAAB.ExecuteDataset(ConnectionString, CommandType.Text, ToString(), _params.ToArray())
                   : DAAB.ExecuteDataset(ConnectionString, CommandType.Text, ToString());

        }

        /// <summary>
        /// Executes ther query and adds the results to the provided dataset
        /// </summary>
        /// <param name="data">The dataset to fill with this query</param>
        /// <returns>The dataset passed in</returns>
        public DataSet ExecuteDataset(DataSet data)
        {
            DataSet localdata;
            localdata = (HasParams)
                       ? DAAB.ExecuteDataset(ConnectionString, CommandType.Text, ToString(), _params.ToArray())
                       : DAAB.ExecuteDataset(ConnectionString, CommandType.Text, ToString());
            // Make sure the table names match
            if (data.Tables.Count == 1 && localdata.Tables.Count == 1)
                localdata.Tables[0].TableName = data.Tables[0].TableName;

            data.Merge(localdata, false, MissingSchemaAction.Ignore);
            return data;
        }

        #endregion
        

        #region "Object Hydration"

        #region "Cache"

        /// <summary>
        /// Generic cache class to cache object graphs and type converters
        /// </summary>
        private static class Cache
        {
            static Dictionary<string, object> _cache = new Dictionary<string, object>();


            public static bool Contains(String key) { return _cache.ContainsKey(key); }
            public static object GetValue(String key)
            {
                return (_cache.ContainsKey(key)) ? _cache[key] : null;
            }
            public static void Add(String key, object data)
            {
                if (_cache.ContainsKey(key))
                    _cache[key] = data;
                else
                    _cache.Add(key, data);
            }
            public static void Remove(string key)
            {
                if (_cache.ContainsKey(key)) _cache.Remove(key);
            }
        }

        #endregion


        #region "GetValue / TypeConverters"

        public interface ITypeConverter { object GetValue(Type fieldType, object value); }

        /// <summary>
        /// Adds a custom type converter. When hydrating an object, certain complex types might have special needs 
        /// when it comes to deserializing from database. You can add a customer converter for the type, in order to 
        /// have the auto hydration use the this type converter instead of the Default type converter
        /// </summary>
        /// <param name="typeName">Full name of the type to use the converter for</param>
        /// <param name="converter">The converter oject to use. It must implement the ITypeConverter interface</param>
        public static void AddTypeConverter(string typeName, ITypeConverter converter)
        {
            typeName = typeName.ToLower();
            var list = GetAllConverters();
            if (list.ContainsKey(typeName))
                list[typeName] = converter;
            else
                list.Add(typeName, converter);
        }

        /// <summary>
        /// Retreives a list of ITypeConverters in the system
        /// </summary>
        private static Dictionary<String, ITypeConverter> GetAllConverters()
        {
            const string key = "TypeConverters";
            if (!Cache.Contains(key))
            {
                var types = new Dictionary<String, ITypeConverter>();
                Cache.Add(key, types);
            }
            return (Dictionary<String, ITypeConverter>)Cache.GetValue(key);
        }

        /// <summary>
        /// Gets the database value converter for a certain Type name
        /// </summary>
        /// <param name="typeName">The full name of the type e.g. System.String</param>
        /// <returns>A ITypeConverter object from the cache</returns>
        private static ITypeConverter GetTypeConverter(String typeName)
        {
            typeName = typeName.ToLower();
            var converters = GetAllConverters();
            return (converters.ContainsKey(typeName)) ? converters[typeName] : null;
        }

        /// <summary>
        /// Converts a database value to its object representation. Uses the TypeConverter cache to properly translate complex types
        /// </summary>
        /// <param name="fieldType">The Type of the field to convert to</param>
        /// <param name="value">The database value. e.g. the object from the data reader ordinal</param>
        /// <returns>A properly converted object</returns>
        public static object GetValue(Type fieldType, object value)
        {
            var typeName = fieldType.Name;
            object newValue = null;
            Type baseType = fieldType.BaseType;

            // Check if an empty value or an empty string
            if (value == null || value.ToString() == String.Empty)
                return newValue;

            if (fieldType.Equals(value.GetType()))
            {
                newValue = value;
            }
            else if (typeName == "Boolean")
            {
                newValue = (value.ToString() == "1" ||
                            value.ToString().ToLower() == "on" ||
                            value.ToString().ToLower() == "true" ||
                            value.ToString().ToLower() == "yes") ? true : false;
            }
            // Nullable types's name starts with nullable
            else if (typeName.StartsWith("Nullable"))
            {
                var typeFullName = fieldType.FullName;
                if (typeFullName.Contains("DateTime"))
                    newValue = Convert.ToDateTime(value);
                else if (typeFullName.Contains("Boolean"))
                    newValue = Convert.ToBoolean(value);
                else if (typeFullName.Contains("Int16"))
                    newValue = Convert.ToInt16(value);
                else if (typeFullName.Contains("Int32"))
                    newValue = Convert.ToInt32(value);
                else if (typeFullName.Contains("Integer"))
                    newValue = Convert.ToInt32(value);
                else if (fieldType.FullName.Contains("Int64"))
                    newValue = Convert.ToInt64(value);
                else if (fieldType.FullName.Contains("Decimal"))
                    newValue = Convert.ToDecimal(value);
                else if (typeFullName.Contains("Double"))
                    newValue = Convert.ToDouble(value);
                else if (typeFullName.Contains("Single"))
                    newValue = Convert.ToSingle(value);
                else if (typeFullName.Contains("UInt16"))
                    newValue = Convert.ToUInt16(value);
                else if (typeFullName.Contains("UInt32"))
                    newValue = Convert.ToUInt32(value);
                else if (typeFullName.Contains("UInt64"))
                    newValue = Convert.ToUInt64(value);
                else if (typeFullName.Contains("SByte"))
                    newValue = Convert.ToSByte(value);
            }
            else if (fieldType.FullName.Equals("System.Guid"))
            {
                newValue = new Guid(value.ToString());
            }
            else if (baseType != null && fieldType.BaseType == typeof(Enum))
            {
                int intEnum;
                if (int.TryParse(value.ToString(), out intEnum))
                    newValue = intEnum;
                else
                {
                    try
                    {
                        newValue = Enum.Parse(fieldType, value.ToString());
                    }
                    catch (Exception)
                    {
                        newValue = Enum.ToObject(fieldType, value);

                    }
                }
            }
            else if (fieldType.FullName.Equals("System.Guid"))
            {
                newValue = new Guid(value.ToString());
            }
            else
            {
                // Try to get a specific type converter
                //      when no type converter is foudn then do a brute convert and ignore any errors that come up                
                var converter = GetTypeConverter(fieldType.Name);
                if (converter != null)
                {
                    newValue = converter.GetValue(fieldType, value);
                }
                else
                {
                    try
                    {
                        newValue = Convert.ChangeType(value, fieldType);
                    }
                    catch (Exception) { }
                }
            }


            return newValue;

        }

        #endregion


        #region "FillObject / FillCollection | DataReader"

        /// <summary>
        /// Fills an object using generics from a data reader object
        /// </summary>
        /// <typeparam name="T">The type of the object to fill</typeparam>
        /// <param name="dr">The data reader object used to hydrate the object</param>
        /// <returns>A hydrated object of type T</returns>
        public static T FillObject<T>(DbDataReader dr)
        {
            return FillObject<T>(dr, true);
        }

        /// <summary>
        /// Fills a collection of objects using generics from a data reader object
        /// </summary>
        /// <typeparam name="T">The Type of the collection item object to fill</typeparam>
        /// <param name="reader">The reader object used to hydrate the collection</param>
        /// <returns>Collection of type of type T</returns>
        public static List<T> FillCollection<T>(DbDataReader reader)
        {
            var objCollection = new List<T>();

            try
            {
                while (reader.Read())
                {
                    objCollection.Add(CreateObject<T>(reader));
                }
            }
            finally
            {
                reader.Close();
            }

            return objCollection;
        }
        
        /// <summary>
        /// Fill a particular object
        /// </summary>
        /// <typeparam name="T">The type of object to fill</typeparam>
        /// <param name="dr">The reader object used to hydrate the object</param>
        /// <param name="manageDataReader">When set to true, closes the reader when finished</param>
        /// <returns>A hydrated object of type T</returns>
        private static T FillObject<T>(DbDataReader dr, bool manageDataReader)
        {
            var objFillObject = default(T);
            // Make sure the data reader has data
            if (manageDataReader && dr.Read() == false) return objFillObject;

            // Fill the object            
            objFillObject = CreateObject<T>(dr);

            // Close the reader when in charge
            if (manageDataReader) dr.Close();

            // Return the filled object
            return objFillObject;
        }

        private static T CreateObject<T>(DbDataReader dr)
        {
            // Create a new instance of the object
            var objObject = Activator.CreateInstance<T>();

            // Check weather the object is a value type
            if (objObject.GetType().IsValueType)
            {
                var value = GetValue(objObject.GetType(), dr.GetValue(0));
                if (value != null) objObject = (T)value;
                return objObject;
            }

            // Hydrate a complex type it
            //  Get the fields for the type
            List<object> fields = GetFields(objObject);

            //  Get the ordinals in the data reader
            int[] arrOrdinals = GetOrdinals(fields, dr);

            for (int i = 0; i < fields.Count; i++)
            {
                var field = fields[i];

                //   Make sure the value is found
                if (arrOrdinals[i] != -1)
                {
                    //  Get the value from the reader
                    var value = dr.GetValue(arrOrdinals[i]);

                    //  Make sure the value is not null before assigning
                    if (value == DBNull.Value) continue;

                    // Check weather the member is a property or a field and fill it accordingly
                    if (field is FieldInfo)
                        (field as FieldInfo).SetValue(objObject, GetValue(((FieldInfo)field).FieldType, value), BindingFlags.Default, null, null);
                    else if (field is PropertyInfo)
                        (field as PropertyInfo).SetValue(objObject, GetValue(((PropertyInfo)field).PropertyType, value), BindingFlags.Default, null, null, null);
                }
            }

            return objObject;
        }

        /// <summary>
        /// Match the bject fields against the ordinal of the DataReader. The ordinal of the DataReader is used 
        /// Rather than the string indexer to maximize performance
        /// </summary>
        /// <param name="fields">The list of members to hydrate for the object</param>
        /// <param name="dr">The data reader to map the ordinals from</param>
        /// <returns></returns>
        private static int[] GetOrdinals(List<object> fields, DbDataReader dr)
        {
            var arrOrdinals = new int[fields.Count];
            var columns = new Hashtable();

            // Get the column names
            for (var ci = 0; ci < dr.FieldCount; ci++)
                columns[dr.GetName(ci).ToUpperInvariant()] = "";

            // Match the fields to the column name ordinal
            for (var fi = 0; fi < fields.Count; fi++)
            {
                string fieldName = (fields[fi] is FieldInfo)
                                            ? ((FieldInfo)fields[fi]).Name.ToUpperInvariant()
                                            : ((PropertyInfo)fields[fi]).Name.ToUpperInvariant();

                if (columns.ContainsKey(fieldName))
                    arrOrdinals[fi] = dr.GetOrdinal(fieldName);
                else
                    arrOrdinals[fi] = -1;
            }

            return arrOrdinals;

        }

        

        #endregion

        /// <summary>
        /// Get the fields / properties to hydrate for an object. 
        /// Caches the object map in order to maximize performance. 
        /// So reflection is used only first time on n object type
        /// </summary>
        /// <param name="obj">Object to use to hydrate</param>
        /// <returns>A list of Fields and Properties</returns>
        private static List<object> GetFields(object obj)
        {
            var cacheKey = "reflectioncache_" + obj.GetType().FullName;
            List<object> fields;
            if (Cache.Contains(cacheKey))
                fields = Cache.GetValue(cacheKey) as List<object>;
            else
            {
                fields = new List<object>();
                foreach (PropertyInfo p in obj.GetType().GetProperties())
                {
                    if (p.CanWrite) fields.Add(p);
                }
                foreach (FieldInfo f in obj.GetType().GetFields())
                {
                    if (f.IsPublic && !f.IsStatic) fields.Add(f);
                }

                fields.AddRange(obj.GetType().GetFields());

                Cache.Add(cacheKey, fields);
            }
            return fields;
        }
        #endregion

    }
    
}
